Extensive work has been performed during the last ten years to build and investigate photonic crystals, the optical analogues to electronic semiconductors. Photonic crystals are materials built to present a periodic variation of refractive index. The periodicity being the same order of magnitude as the wavelength of the electromagnetic (EM) waves, these structures exhibit band gaps for photons. The propagation of the EM waves can be controlled by changing the periodicity and introducing point or line defects in the photonic crystal. A. Birner et al in, “Silicon-based photonic crystals,” Adv. Mater. 13, 377–388 (2001), recently reviewed 1D, 2D, and 3D photonic crystals made out of silicon.
Foresi et al in, “Photonic-bandgap microcavities in optical waveguides,” Nature 390, 143–145 (1997) disclose that 1D structures and Birner et al in, “Transmission of microcavity structure in a two-dimentional photonic crystal based on macroporous silicon,” Materials Science in Semiconductor Processing 3, 487–491 (2000), disclose that 2D structures are usually built by drilling well-controlled pores in a silicon wafer by electrochemical etch or by electron beam lithography. In, “Large-scale synthesis of a silicon photonic crystal with a complete three-dimensional bandgap near 1.4 micrometer,” Nature 405, 437–440 (2000), Blanco et al disclose that 3D structures usually involve the growth of a crystal by chemical vacuum deposition on a periodic template followed by the dissolution of the template (inverse opal structure).